Immunology MS L3 Flashcards
Virus vs bacteria APC
-Viruses infecting dendritic cell
-Bacteria infecting macrophage
2 types of T cells
- Helper T cells (CD4) or Th cell - activate macrophages, DCs (APCs), activate Cytotoxic T cells and B cells
- Cytotoxic T cells (CD8) or Killer T cells - kill infected cells, similar to NK cells but need education and activation
Role of B cells?
- Produce antibodies
B cells differentiate into Plasma cells that make antibodies
Make - IgM, IgA, IgG, IgE, IgD
Produce antibodies via innate and adaptive mechanisms - Need to talk to CD4 T cells first
B cell - Antibody types
IgM - nonspecific, pentamer
IgG - in blood and lymphatics, long term memory
IgA - serum, mucosal secretion
IgE -allergy-parasite
IgD -B cell development
Functions of cytokines?
-Activate macrophages, neutrophils, cytotoxic T cells and B cells
-Suppress immune cell activation
-Immune regulation
How do T Helper (Tfh) cells help B cells become plasma cells (antibody producing cells)
- Activated follicular B cells express CCR7 and migrate to T/B boundary
- Activated T cells express CXCR5, reduce CCR7 expression, and migrate toward B cells
- B cells receive T cell help and differentiate into memory B cells or plasmablasts
What happens when B cells encounter antigen within 24 hours post infection/immunisation?
- Antigens enter the lymph node via afferent lymphatics at the subscapular sinus
- Antigens are captured by subscapular sinus macrophages and presented to B cells
- Antigens get transported to follicular dendritic cells for affinity maturation
How do dendritic cells become competent to stimulate T cells?
- Immature dendritic cell recognizes PAMPS and become activated
- TLR signaling induces CCR7 and enhances processing of pathogen-derived antigens
- Dendritic cells mi´grate to the draining lymph node via CCR7
- Dendritic cells present antigenic peptide on MHC to naive T cells in the lymph node
Process of adaptive immunity?
1.Virus infects and replicates within the epithelium
2. Dendritic cell activation
3. T and B cell priming in the lymph node
4. Adaptive immunity
